Washington: Cholesterol levels usually go up in colder months - a trend that may be driven by behavioural changes that occur with the changing seasons, new research by an Indian-American researcher shows.

While previous studies have shown that heart attacks and heart-related deaths increase during the winter, researchers at Johns Hopkins' Ciccarone Center for the Prevention of Heart Disease were interested in finding out whether cholesterol parameters might follow a similar pattern.

They studied a massive data representing 2.8 million adults - the largest study so far to look at seasonal lipid trends in adults.

"We found that people tend to have worse cholesterol numbers on average during the colder months than in the warmer months - not by a very large amount, but the variation is significant," said Parag Joshi, a cardiology fellow at Johns Hopkins Hospital.

"The data instead validates a clear seasonal pattern and underscores the need to pay attention to behaviours that are critical to minimising cardiovascular risk," Joshi said.

"In the summer, we tend to get outside, we are more active and have healthier behaviours overall," Joshi added.

"In the colder months, we tend to crawl into our caves, eat fat-laden comfort foods and get less exercise, so what we see is that LDL and non-HDL bad cholesterol markers are slightly worse," he added. So you have a lipid signature of higher risk but it is driven by behaviors that occur with the changing seasons.

Researchers speculate the shorter days of winter - and limited time spent outside - also mean less sun exposure and, subsequently, lower concentrations of vitamin D, which has also been associated with the ratio of bad to good cholesterol.

More research is needed to further tease out what might be behind these seasonal variations, Joshi told the gathering at the American College of Cardiology's 63rd Annual Scientific Session recently.